Time to Fertilize? Wait a Minute!

For many weekend gardeners, this is also the time when chemicals make their annual debut -- as fertilizers, pesticides or herbicides. In pursuit of a greener lawn or a pest-free garden, homeowners often become chemists of sorts.

Recent studies, however, have raised a red flag on chemical use, pointing out a possible link between herbicides and pesticides and a kind of cancer called non-Hodgkin's lymphoma. Although experts say that more research is needed, what's important for the home gardener is to play it safe.

"Make sure you read the directions," says George C. Hamilton, Ph.D., associate extension specialist for Rutgers Cooperative Extension. "We find that people don't read the labels completely and that can cause problems."

Fertilizers aren't dangerous to handle, but chemicals used to control pests and weeds can be highly toxic. Used incorrectly, pesticides can poison not only people, but also kill off beneficial bugs and contaminate the soil and groundwater, experts say.

Before you bring out your chemical arsenal this year, experts suggest asking yourself several questions:

What is the problem in the garden?

Is it a weed, an insect, or a disease?

Is the problem serious enough to require a pesticide?

What is the safest pesticide to use, and when should it be used?

Fertilizers

Does your lawn really need a fertilizer? J. Robert Nuss, Ph.D., professor of ornamental horticulture at Penn State University, says that, in general, homeowners tend to put too much fertilizer on their lawns.

He recommends that homeowners get a soil test done before laying down any nutrients. For about $10, you can find out whether your lawn needs fertilizer -- and if so, what kind. Soil kits are available at gardening centers and county extension offices.

"A lot of folks approach soil testing as a gimmick to sell fertilizer," Dr. Nuss says. "But it's more important in today's economy, as well as for ecology. It avoids over-application of fertilizer."

You can also go overboard on fertilizer for flowering plants, Dr. Nuss says. Too much fertilizer will encourage the plant to grow more leaves -- and cut back on flower production. "All you have left is a green, leafy plant," he says.

More growth also means more pruning, and thus more yard litter to dispose of.

Pesticides

If you decide to use a pesticide or herbicide, experts say you should first zero in on the problem: What kind of weed is it? What kind of insect? What kind of plant is the insect attacking?

"One product won't control everything," Dr. Hamilton says. A chemical that works on tomatoes may not work on eggplants, even though those two vegetables are closely related.

Timing is also critical. If you're trying to control dandelions, make sure you use the herbicide at the right time of year. Too early or too late in the season may not be effective, Dr. Hamilton says.

Some chemicals may require that you water the plant after applying the pesticide, to ensure that the chemical gets into the soil. Others may need dry conditions.

The experts also stress safety precautions when using any of these chemicals. Wear rubber gloves and long sleeves to avoid getting the chemical on your skin. You may also need to use a respirator, a hat or foot protection. Leather gloves or hats should not be used because they can absorb chemicals.

Use separate spray systems for herbicides and pesticides, so that the residues don't mix together. A tiny bit of herbicide left in a pesticide applicator, for instance, could damage a rose bush, Dr. Hamilton says.

Mix only enough of the pesticide to treat the problem. Dry pesticides can be stored safely for a season, but liquid pesticides must be treated as hazardous wastes, and disposed of through a county hazardous waste program. Never pour them down the drain.

Never carry a pesticide in the passenger area of your car, or place it next to food items in the trunk. Never store the chemicals in anything other than their original containers, to avoid possible poisoning. Dr. Hamilton tells of several poisoning cases in which a brown chemical was stored in a soda bottle, and other chemicals were mixed and stored in milk jugs.

Alternatives to chemicals

One way to cut back on herbicide use is to mulch, particularly for annual plants, Dr. Nuss says. Mulching keeps down weed growth.

For pest control, an example of a nonchemical approach is a method used for tent caterpillars. "There's no reason to spray," Dr. Hamilton says. "You just wait until all the caterpillars are in the tent and cut out the tent."

Check with your garden center or extension office for more ideas on nonchemical alternatives to pesticides.

Another approach is vigilance, Dr. Nuss says. Pull out that weed as soon as it appears. Pick off the bug when you first notice it on the plant.

"Most folks say, 'I'll wait until next week,' and by then the weed has flowers and seeds," Dr. Nuss says. "Good vigilance pays off."

Reading the labels

Once you've identified the garden problem, gardening experts recommend buying a pesticide based on its relative safety, its ease of use and its effectiveness for the problem. Here is a list of toxicity warnings and their explanations, from the Florida Cooperative Extension Service:

Danger-Poison. These are the most toxic pesticides and should be handled with extreme care.

Warning. These are moderately toxic materials. They should be handled with care.

Caution. These are slightly toxic materials that are still poisonous. Handle as you would any poison -- carefully.

Pesticide mixing and application tips

The Florida Cooperative Extension Service offers these tips for safety when using pesticides:

Use a 1- to 3-gallon hand-held sprayer, and check with plain water before filling with pesticide, looking for leaks or plugged nozzle. Do not use a backpack sprayer, because it can leak onto your back.

Be especially careful when mixing a pesticide. Always have another adult in the area in case of an accident. Follow the label directions precisely. Have water, soap, towels, and a hose on hand in case of a spill. Mix only in a well-ventilated area.

Keep other people and pets away when applying the pesticide. The label will tell you whether children and pets should be barred from the treated area.

Clean the applicator and sprayer thoroughly after use.

Immediately after applying a pesticide and cleaning the applicator, wash your clothes in hot water with a strong detergent. Do not wash them with other clothing. Take a hot shower and wash your hair.